The appeal of tree houses is fairly obvious: seclusion, sustainability, coziness, communion with nature. Of course, often times those are qualities that are felt rather than understood—there’s a reason that, for many youngsters, the first real architectural impulse is to want a nest among the trees. But tree houses can retain their magic for adults, too. And as a gorgeous new book from Taschen shows, when that childhood dream is realized with grown-up resources, the results can be truly stunning.

Tree Houses: Fairy Tale Castles in the Air is a 350-page tome that collects 50 diverse tree houses from around the globe. In some cases, the structures are houses in the truest sense; one section is dedicated to the Kombai tribe of Indonesia, who build homes at dizzying heights of over a hundred feet in trees in the foothills of the Jayawijaya Mountains. Others are built for specific activities, like the Meditation Tree House, a simple structure, erected outside Rome, which offers a tranquil space for the owner to reflect.

But many of the projects included take vastly more experimental forms. And if you’re already uprooting convention and building a house in a tree, why not? The Free Spirit Spheres, located in British Columbia, are a series of hanging spherical cabins, connected by a series of rope ladders that borrow from sailboat riggings (adventurous travelers can rent the tree balls on a nightly basis). The Lake Nest Tree House, in New York, is representative of another tree-house microtrend, essentially a bird’s nest built at human scale. The Honey Sphere tree house, built in Beverly Hills, does away with walls and ceilings altogether—it was built by Robby Krieger, guitarist for The Doors, as a place to observe nature, and it’s little more than a platform encircled by an elegant geodesic sphere.

The grandaddy of them all, however, has to be Horace’s Cathedral (also known as the Minister’s House), built by Horace Burgess in Crossville, Tennessee. Burgess started construction on the tree house in 1993, after being instructed to do so by God himself. And it’s hard to imagine Him being disappointed. Burgess’s tree house is thought to be the biggest in the world, with an estimated floor area of around 9,000 square feet. There can’t be many tree houses out there that can comfortably accommodate a full-size basketball hoop.

But for all the wild variety found between the book’s covers, one common thread can be found among the book’s projects: The vast majority were constructed in the last few years. That could be because, in the last decade or so, we’ve seen an explosion of buildings that push the boundaries of what a tree house can be. But it also might have something to do with the fact that, when you’re up in the sky, upkeep is tough, and sometimes those fairy tale castles meet with the harsh realities of the elements.